1. Field of the Invention
The present invention relates to a coupling structure between a circuit board and a frame member, which is suitable for various electrical devices or electronic circuit units.
2. Description of the Related Art
FIG. 4 is a perspective view of a main portion of a conventional coupling structure between a circuit board and a frame member. Referring now to FIG. 4, the conventional coupling structure between a circuit board and a frame member is described. A frame member 51 is made of a rectangular metal material, and has an L-shaped tongue 51a that is cut out and bent toward an inner portion of the frame member 51 and an opening 51b formed by cutting out the tongue 51a. 
A circuit board 52 has a cut-out 52a opposite to the tongue 51a. In addition, a wiring pattern 53 is formed on the circuit board 52. A land portion 53a formed at the end of the wiring pattern 53 extends up to the cut-out 52a. 
The circuit board 52 is set in the frame member 51. Under such conditions that the tongue 51a is positioned in the cut-out 52a, a solder 54 applied to a corner formed by the tongue 51a and the circuit board 52 bonds the frame member 51 to the land portion 53a to thereby complete the conventional coupling structure between a circuit board and a frame member (see Japanese Unexamined Patent Application Publication No. 10-341087, for instance).
However, the conventional coupling structure between a circuit board and a frame member has a problem in that a capillarity effect of the solder 54 applied to the corner formed by the tongue 51a and the circuit board 52 is lowered, and the solder 54 flows more toward the inner portion of the frame member 51 to reduce adhesion between the frame member 51 and the land portion 53a. Moreover, if applied to an RF unit, the conventional structure involves a problem of low shielding effect because of the opening 51b. 